Method for fabricating multi-layer film for vacuum packaging and multi-layer film fabricated by the method

Abstract

A method for fabricating a multi-layer film for vacuum packaging, comprises the steps of: supplying a gas-impermeable film to a cooling roll; supplying a sealing film to a nip roll having an embossed pattern; extruding a molten polymer material toward a gap between the gas-impermeable film and the sealing film, thereby forming a multi-layer preform having a structure of gas-impermeable film-polymer layer-sealing film; and squeezing the multi-layer preform by passing the multi-layer preform through a nip between the nip roll and the cooling roll, so that the gas-impermeable film, the sealing film, and the polymer material of the multi-layer preform are laminated on each other simultaneously while the sealing film and the polymer material are embossed by the nip roll and the cooling roll.

1 . A method for fabricating a multi-layer film for vacuum packaging, the method comprising the steps of: 
 supplying a gas-impermeable film to a cooling roll;    supplying a sealing film to a nip roll having an embossed pattern;    extruding a molten polymer material toward a gap between the gas-impermeable film and the sealing film, thereby forming a multi-layer preform having a structure of gas-impermeable film-polymer layer-sealing film; and    squeezing the multi-layer preform by passing the multi-layer preform through a nip between the nip roll and the cooling roll, so that the gas-impermeable film, the sealing film, and the polymer material of the multi-layer preform are laminated on each other simultaneously while the sealing film and the polymer material are embossed by the nip roll and the cooling roll.    
   
   
       2 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 1 , wherein the sealing film is a polyolefin-based film containing one selected from the group consisting of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene (PP), ethylene-vinylacetate copolymer (EVA), ethylene-acryl acid copolymer (EAA), and ethylene-methylacrylate copolymer (EMA).  
   
   
       3 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 1 , wherein the gas-impermeable film includes at least one layer made from a polyolefin-based material, and each of the sealing film and the polymer layer is a polyolefin-based film.  
   
   
       4 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 1 , wherein the gas-impermeable film is a complex film fabricated by laminating or co-extruding a nylon film, a polyester film, and an ethylene-vinyl alcohol copolymer (EVOH) film.  
   
   
       5 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 1 , wherein the gas-impermeable film is a complex film fabricated by laminating or co-extruding polyolefin with at least one of a nylon film, a polyester film, and an ethylene-vinyl alcohol copolymer film.  
   
   
       6 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 2 , wherein the polymer material is a polyolefin-based material equal to that from which the sealing film is made.  
   
   
       7 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 2 , wherein the sealing film contains, as additives, at least one of an antibiotic material, an anti-fog material for preventing formation of droplets, and an aromatic material for providing fragrance to the sealing film.  
   
   
       8 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 2 , wherein the sealing film is an air-cooled film fabricated through an extrusion according to a blown method.  
   
   
       9 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 1 , further comprising a step of preheating the gas-impermeable film and the sealing film before the polymer material is extruded.  
   
   
       10 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 1 , wherein the gas-impermeable film has an oxygen permeability smaller than or equal to 200 cc/m 2 ·24 hrs·atm.  
   
   
       11 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 1 , wherein the embossed pattern has a shape selected from the group consisting of shapes of parallel lines, slant lines, wave lines, spiral lines, and crossing lines thereof.  
   
   
       12 . A method for fabricating a multi-layer film for vacuum packaging as claimed in  claim 11 , wherein the embossed pattern includes at least one of a letter and a character in addition to the selected shape.  
   
   
       13 . A multi-layer film for vacuum packaging, comprising: 
 a gas-impermeable film;    a sealing film having an embossed pattern formed thereon; and    a polymer layer formed between the gas-impermeable film and the sealing film and having the embossed pattern formed thereon, wherein    the gas-impermeable film, the sealing film, and the polymer layer are laminated on each other simultaneously while the embossed pattern is formed on the sealing film and the polymer layer by extrusion-coating a molten polymer material into a gap between the gas-impermeable film passing via a cooling roll and the sealing film passing via a nip roll adjacent to the cooling roll and then passing a multi-layer perform consisting of the gas-impermeable film-polymer layer-sealing film through a nip between the nip roll and the cooling roll in a squeezed state, the nip roll having an embossing pattern.    
   
   
       14 . A multi-layer film for vacuum packaging as claimed in  claim 13 , wherein the sealing film is a polyolefin-based film containing one selected from the group consisting of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene (PP), ethylene-vinylacetate copolymer (EVA), ethylene-acryl acid copolymer (EAA), and ethylene-methylacrylate copolymer (EMA).  
   
   
       15 . A multi-layer film for vacuum packaging as claimed in  claim 13 , wherein the gas-impermeable film includes at least one layer made from a polyolefin-based material, and each of the sealing film and the polymer layer is a polyolefin-based film.  
   
   
       16 . A multi-layer film for vacuum packaging as claimed in  claim 13 , wherein the gas-impermeable film is a complex film fabricated by laminating or co-extruding a nylon film, a polyester film, and an ethylene-vinyl alcohol copolymer (EVOH) film.  
   
   
       17 . A multi-layer film for vacuum packaging as claimed in claims  13 , wherein the gas-impermeable film is a complex film fabricated by laminating or co-extruding polyolefin with at least one of a nylon film, a polyester film, and an ethylene-vinyl alcohol copolymer film.  
   
   
       18 . A multi-layer film for vacuum packaging as claimed in  claim 14 , wherein the polymer material is a polyolefin-based material equal to that from which the sealing film is made.  
   
   
       19 . A multi-layer film for vacuum packaging as claimed in  claim 14 , wherein the sealing film contains, as additives, at least one of an antibiotic material, an anti-fog material for preventing formation of droplets, and an aromatic material for providing fragrance to the sealing film.  
   
   
       20 . A multi-layer film for vacuum packaging as claimed in  claim 14 , wherein the sealing film is an air-cooled film fabricated through an extrusion according to a blown method.  
   
   
       21 . A multi-layer film for vacuum packaging as claimed in  claim 13 , wherein the gas-impermeable film has an oxygen permeability smaller than or equal to 200 cc/m 2 ·24 hrs·atm.  
   
   
       22 . A multi-layer film for vacuum packaging as claimed in  claim 13 , wherein the embossed pattern has a shape selected from the group consisting of shapes of parallel lines, slant lines, wave lines, spiral lines, and crossing lines thereof.  
   
   
       23 . A multi-layer film for vacuum packaging as claimed in  claim 22 , wherein the embossed pattern includes at least one of a letter and a character in addition to the selected shape.  
   
   
       24 . A vacuum packaging bag comprising a multi-layer film for vacuum packaging according to  claim 13.